The document US 2004/0094757 discloses a prior art wavelength-converting reaction resin compound with which phosphor particles are admixed. The phosphor particles have particularly large diameters, their d50 values, measured in Q3, being provided as preferably between 10 μm inclusive and 20 μm inclusive. The d50 value is to be understood as the median diameter determined on the basis of a distribution sum of the particles. “Q3” here stands for the mass distribution sum or the volume distribution sum. When such large phosphor particles are used, a thixotropic agent is added to the reaction resin compound to prevent the particles from sedimenting in it.